Deareating Feed Tank

Deareating Feed Tank

A Deaerating Feed Tank (DFT), often found in steam plants that propel ships, is located after the main condensate pump and before the main feed booster pump.

From the theoretical Rankine cycle diagram, there are four main processes, or steps:

1 to 2 Water is raised from a low pressure to a high pressure (Pump work in) (feedwater pump)

2 to 3 Water is heated to boiling (Heat input) (steam generator)

3 to 4 Steam is expanded in a turbine (Work out) (turbine)

4 to 1 Wet vapor is condensed (condensing) (surface condenser)

In the practical implementation of a Rankine cycle, it is common to break the single pump (process 1 to 2) into three pumps: (in water flow order: condensate pump, feed booster pump and then feedwater pump). The DFT has three purposes:

1. Remove dissolved oxygen (“air”) from the condensate
2. Pre-heat the feedwater
3. Provide a storage/surge volume